CLINICAL CASES
Kamila Kocent
1, A–D, Ryszard Koczorowski
2, A, C, D–FThe Use of the Herbst Appliance in the Treatment of
Adult Patients with Skeletal Class II Malocclusion
Zastosowanie aparatu Herbsta w leczeniu dorosłych pacjentów
z II klasą szkieletową
1 Specialist Dental Clinic NORDENT, Poznań, Poland
2 Department of Gerodontology, Poznan University of Medical Sciences, Poznań, Poland
A – research concept and design; B – collection and/or assembly of data; C – data analysis and interpretation; D – writing the article; E – critical revision of the article; F – final approval of article
Abstract
The growing number of adult patients interested in orthodontic treatment for aesthetic and health-related reasons has been a subject of numerous discussions among dentists dealing with the improvement of external appearance. The Herbst appliance, also known as the Herbst hinge, is one of the alternative methods of orthodontic treatment for adult patients with skeletal class II malocclusion. On account of its mechanism, the Herbst appliance is com-pared to an artificial temporomandibular joint. The paper presents adult therapy cases in which the aforementioned appliance has been used. The authors discuss its advantages, working principle and therapeutic procedures related to the Herbst appliance which, though first introduced in the early 20th century, has recently enjoyed a revival.
Cemented on selected teeth, the appliance works continuously and, other than proper hygiene care, it does not require particular attention from the patient. The authors present the state of the masticatory organ prior to and following the treatment involving the appliance. Several years of patient observation by the attending orthodontist warrant the recognition of this therapeutic method as highly useful in treating skeletal class II malocclusion type owing to its immediate, lasting and satisfying aesthetic results (Dent. Med. Probl. 2014, 51, 2, 265–274).
Key words: Herbst appliance, malocclusion, skeletal class II, orthodontic treatment of adults.
Streszczenie
Zwiększenie liczby dorosłych pacjentów zainteresowanych leczeniem ortodontycznym zarówno z przyczyn este-tycznych, jak i zdrowotnych jest tematem licznych dyskusji stomatologów zajmujących się poprawą zewnętrznego wizerunku. Aparat Herbsta zwany zawiasem Herbsta jest jedną z alternatywnych metod ortodontycznej terapii pacjentów z II klasą szkieletową. Ze względu na mechanizm działania jest porównywany do sztucznej formy stawu skroniowo-żuchwowego. Celem pracy jest przedstawienie przypadków leczenia dorosłych pacjentów z zastosowa-niem wyżej wymienionego aparatu. Autorzy przedstawiają zalety, mechanizm działania i procedury lecznicze zwią-zane z aparatem Herbsta, który choć został po raz pierwszy zaprezentowany na początku XX w., to obecnie przeżywa swój renesans. Zacementowany na wybranych zębach aparat działa przez 24 godziny na dobę i oprócz zapewnienia dobrej higieny nie wymaga koniecznej współpracy ze strony pacjenta. Autorzy opisują stan narządu żucia przed lecze-niem z użyciem tego aparatu i po leczeniu. Kilkuletnie monitorowanie wielu pacjentów przez prowadzącego lekarza ortodontę pozwala uznać tę metodę terapii za bardzo przydatną w leczeniu wymienionej wady zgryzu z uwagi na szybkie, długotrwałe i satysfakcjonujące efekty estetyczne (Dent. Med. Probl. 2014, 51, 2, 265–274).
Słowa kluczowe: aparat Herbsta, wady zgryzu, klasa II szkieletowa, leczenie ortodontyczne dorosłych. Dent. Med. Probl. 2014, 51, 2, 265–274
ISSN 1644-387X © Copyright by Wroclaw Medical University and Polish Dental Society
Modern day orthodontic treatment based on the latest technologies enables the achievement of fully satisfying effects to both the patients and their den-tist, using various techniques and methods. Apart
from the broadly defined ideal treatment results, pa-tients expect reductions in therapy time and expen-diture. There has been an increase in the number of adult patients who are interested in orthodontic
treatment for both aesthetic and health-related rea-sons [1–3]. Some of the most commonly used treat-ment methods in skeletal class II malocclusion (pos-terocclusion) patients include the following:
− fitting of ribbon arch appliances with elastic class II traction,
− use of orthodontic camouflage, which requires the extraction of the upper two premolars and the retraction of the upper incisors,
− treatment of serious class II cases associated with a surgical procedure [4, 5].
Contrary to adolescent patients, adult patients have lost the benefit of growth spurts, which in-volve the most noticeable mandible growth as well as orthognatic difficulties. The recommended class II elastic traction types are not always condu-cive to the attainment of the anticipated effect, i.e. forward mandible growth, and the frequent lack of discipline in wearing them additionally hinders the quick achievement of therapeutic goals. The extraction of the first premolars in the upper arch does not improve the patient’s profile, nor does it broaden their upper respiratory tract or eliminate speech defects. When proposed treatment associ-ated with orthognatic surgery, patients frequently decline to undergo the prospective procedure, of-ten claiming that backward mandible positioning does not affect the quality of their lives, thus de-ciding to merely align their teeth so as to harmo-nize their dental arches. Therefore, the following question arises: what type of treatment should be employed in order to treat a skeletal class II patient as quickly and effectively as possible while ensur-ing a satisfyensur-ing aesthetic result?
One of the effective methods of orthodon-tic therapy can be the increasingly frequent use
of the Herbst appliance, also known as the Herbst hinge [2, 4, 6–8] (Fig. 1). First presented in 1909 at the International Dental Congress in Berlin, this functional appliance is currently enjoying a ma-jor revival, gaining increasingly numerous ranks of proponents thanks to its high success rate. Rein-troduced in the 1970 and used extensively by Pan-cherz, the Herbst appliance restores the backward positioning of the mandible to its frontal position, both for occluded and unoccluded dental arches. The position of the lips and tongue changes along with the action of the entire group of masticatory organ muscles. Thus, this appliance is referred to as functional appliance [6, 9]. In their assumptions concerning functional orthodontics, Andresen and Häupl, followed by Fränkel and Balters, formulated the principles of functional adjustment within the limits of the masticatory organ [9]. The main prob-lem they encountered using removable functional appliances was the short stimulus functioning pe-riod, where a lasting frontal mandible reposition-ing constitutes a precondition for success. Remov-able orthodontic appliances tend to be removed by the patient in a number of situations on a daily ba-sis, hence the inconsistent duration of their impact. Cemented on selected teeth, the Herbst appliance functions continuously and, other than proper hy-giene care, it does not require particular attention from the patient. The appliance works uninter-ruptedly 24 hours a day, during each activity un-dertaken by the mastication apparatus and may be compared to an artificial form of the temporo-mandibular joint. Since the appliance is equipped with a two-sided, stiff telescopic mechanism, the mandibular condylar process situates itself on the slope of the articular tubercle of the temporal bone
Fig. 1. Anatomical impressions taken with orthodontic bands fitted around abutment teeth in the oral cavity Ryc.1. Wyciski anatomiczne pobrane z pierścieniami dopasowanymi w jamie ustnej do zębów filarowych
and hence limits its retraction. This ensures correct blood flow in the temporo-mandibular joint and proper conditions for its restructuring [5, 8, 10, 11]. In removable appliances, throughout the day the condyle engages in interchangeable forward motion onto the articular tubercle slope during its attachment and backward motion accompanying its removal. This causes the reduction of the blood flow within the joint, thus impeding the restructuring process. The Herbst appliance may at once alter significant overjet (even as large as 10–15 mm), while with removable functional appliances the process occurs gradually and to a limited extent. The imposed forward position of the mandible causes the muscles which retract it, i.e. the temporal muscle and suprahyoid muscles to remain active in the first 3–4 days following the fitting of the Herbst appliance. The telescopic mechanism, however, prevents the mandible from retracting and, as a result, after the aforementioned period of time the muscle tension subsides. This phenomenon may be compared to a weightlifter sustaining a weight above their head. After a short period of time and due to muscle fatigue and decreased muscle tension, the weightlifter drops the weight onto the supporting rack. Paulsen [12] – an avid supporter of the discussed method – stresses that as soon as 3 months following the application of the hinge new bone structures can be observed within temporo-mandibular joints, also among patients past the peak of their growth periods. Manzo [7] argues that the percentage of failed treatments and the predictability of treatment results are comparable to the results of orthognatic procedures, one of the appliance’s benefits being the possibility to obtain class I relation in posterior regions within a period of no more than 10 months. During the Herbst appliance therapy, the upper incisors ought to be aligned so as to gently bite over (overlap with) the lower incisors. They should not, however, be placed in a tête-à-tête position. The alignment of class I canines is a condition for the avoidance of recidivism following the conclusion of active treatment. Throughout the Herbst ap-pliance treatment, orthodontists should take into consideration the following alterations in the posi-tioning of teeth on both dental arches:
– upper jaw molars will distal, while mandibu-lar momandibu-lars will be placed mesially,
– mandibular incisors will be inclined,
– upper jaw molars will be intruded, with man-dibular molars extruded, as a result leading to the reduction of the excessive overbite. The aforementioned will be conducive to treat-ing low angle skeletal class II. With high angle pa-tients, the decision to employ the Herbst appliance should be reconsidered.
It should be noted that skeletal class II patients qualified for treatment using permanent function-al appliances ought to be informed of any possible inconvenience such as:
– hindrances to the maintenance of oral cavity hygiene,
– discomfort related to the irritation of the oral cavity mucus membrane (abrasions, ulcers), – restriction of lateral mandible movement, – hindrances to proper proncunciation and
chewing (initial treatment stage),
– mechanical malfunctions such as the dis-connection of the telescopic mechanism and cracking of orthodontic bands (following their overheating during soldering) or their de-ce-menting.
The structure of the Herbst appliance is based on a two-sided telescopic mechanism fastened to orthodontic pivots soldered to the orthodon-tic bands. The bands, which anchor the appli-ance, are always cemented on the first mandible and upper jaw molars and first premolars [6, 13] (Fig. 2). As of late, it is the lower canines that have been used increasingly as anchors instead of the first premolars. The selection of canines as teeth of greater anchoring capacity stems from the con-ic shape of their anatomcon-ical crowns (as opposed to the cylindrical shape of the first molars). This pre-vents any potential packing of and damage to the gums caused by improperly fitted or cracked bands. Moreover, thanks to its location in the bone trajecto-ry, the canine tends to be more stable than the mo-lar and its forward position on the dental arch facil-itates telescope extension. Thus, the patient will be provided with slightly more room for lateral man-dible movement, while also being able to open their mouth slightly wider. The placement of the orth-odontic bands on the canines also prohibits further intrusion of the first mandible premolars which, to-gether with the second premolars and molars are al-ready affected by the intrusion resulting from the bi-level occlusion plain, typical of skeletal class II.
Placed as described above the bands are then connected with a circular steel section arch 1 mm in diameter, soldered on the palatal side of the up-per arch, and on the side adjacent to the tongue with the lower arch. The anchoring is more sub-stantial when the bands are also connected on the sides adjacent to the cheeks, in both the upper and lower dental arch. This type of anchoring ought to be V-shaped, thus gaining flexibility and limit-ing the risk of arch fracture. Before fittlimit-ing the ap-pliance, the upper incisors should first be properly prepared. This means that skeletal class II, group 2 will require the protrusion of the upper inci-sors in order to gain space suitable for the protrusion of the mandible and achievement of canine class I.
The upper incisors ought to be aligned so as to slightly overbite the lower incisors.
The advantages of the Herbst appliance in-clude the following:
− continuous, round-the-clock impact of the ap-pliance on the mastication apparatus,
− patients are no longer required to cooperate throughout their therapy,
− short orthodontic treatment period (6–8 months on average),
− elimination of permanent teeth extraction, − rapid improvement of the patient’s profile, − quick correction of mandible position, − recognition of appliance efficiency.
Case Reports
The paper presents two case studies involv-ing patients treated at the Specialist Dental Clin-ic NORDENT in Poznań, Poland. Their respective documentation includes: extra- and intraoral clini-cal examination, diagnostic model analyses, cepha-lometric analyses conducted prior to and following the Herbst appliance treatment, as well as photo-graphs of the patients’ faces en face and in profile.
Case 1
An 18-year-old patient reported to the orth-odontic clinic following an attempt to treat maloc-clusion using a segment alignment ribbon arch ap-pliance supported by a removable apap-pliance. The
lack of expected effects convinced the patient to begin an alternative form of treatment. A thera-py using permanent ribbon arch appliances was suggested for the patient’s upper and lower den-tal arch, as well as the Herbst appliance treatment to address the patient’s skeletal class II malocclu-sion. In the course of extraoral clinical examina-tion, a balanced, extended profile was diagnosed with a considerably deeper chin groove.
The following was established in the course of intraoral clinical examination:
1) misaligned upper dental arch with crowded incisors,
2) diastemas in the lower arch, rotated lower ca-nines, inclined lower incisors,
3) angle class II,
4) increased overjet and overbite, 5) satisfactory periodontium condition.
The following was established in the course of cephalometric analysis according to Williams: 1) increased upper incisors inclination angle
= 118.10 degrees,
2) increased lower incisors inclination angle = 109.43 degrees,
3) WITS = 7.01 mm,
4) intermaxillary angle = 19.88 degrees, 5) anteriorization – beta angle = 22.89 degrees, 6) overjet = 6.91 mm,
7) overbite = 4.70 mm, 8) SNB angle = 75.82 degrees.
The new treatment plan assumed the removal of the existing ribbon arch appliance, bracket sand-blasting and their reattachment in order to align
Fig. 2. Components of the Herbst appliance Ryc. 2. Elementy składowe aparatu Herbsta
the upper dentalarch, as well as the alignment of the inclined lower incisor and de-rotation of lower canines along with the closure of the diastemas us-ing a ribbon arch and Herbst appliances.
The following was established in the course of cephalometric analysis following the removal of the Herbst appliance according to Williams: 1) upper incisors inclination angle = 112
de-grees,
2) lower incisors inclination angle = 99 degrees, 3) overjet and overbite in accordance with the
standards, respectively 4 mm and 3.5 mm, 4) WITS = 2 mm,
5) SNB angle = 77.98 degrees.
The Herbst appliance corrected skeletal class II, attaining skeletal class I and teeth class I, respec-tively. The ribbon arch appliance properly aligned
the teeth in the dental arches. The Herbst appli-ance treatment period amounted to 8 months.
Figure 3 presents the patient’s photograph pri-or to pri-orthodontic therapy based on a new treat-ment plan. Figure 4 presents the photograph of pa-tient diagnostic models prior to orthodontic thera-py based on a new treatment plan. Figure 5 presents an intraoral image of the patient with the Herbst appliance. Teleradiographic images were taken both before (Fig. 6a) and after treatment (Fig. 6b). The final figure presents the extraoral image following the removal of the Herbst appliance.
Case 2
A 26-year-old patient reported to the orth-odontic clinic to amend her facial aesthetics and
Fig. 3. Patient’s photographs before orthodontic treatment based on a new therapy plan Ryc. 3. Fotografie pacjenta przed leczeniem ortodontycznym opartym na nowym planie leczenia
Fig. 4. Photograph of patient diagnostic models before orthodontic treatment based on a new therapy plan
mastication apparatus functions (difficulties with biting off, speech impediments – lisp). In the course of extraoral clinical examination, extended profile was diagnosed with a subnasal protrusion and considerably deeper chin groove; labial stoma parted, upper incisors biting over the lower lip.
The following was established in the course of intraoral examination:
1) angle class II,
2) substantially excessive overjet, 3) reduced overbite,
4) significant upper incisors inclination angle, 5) upper and lower dental arch stenosis, 6) proper periodontium condition.
Fig. 5. Patient’s intraoral photograph with the Herbst
appliance
Ryc. 5. Zdjęcie pacjenta wewnątrzustne z aparatem
Herbsta
Fig. 6. Teleradiographic images before treatment (a)
and after removal of the Herbst appliance (b)
Ryc. 6. Zdjęcia teleradiograficzne przed leczeniem (a)
i po zdjęciu aparatu Herbata (b)
The patient’s images prior to and following the treatment are presented in Figures 8, 9, 10, as well as 11a and b, while Figure 12 presents teleradio-graphic images before treatment (12a) and after re-moval of the Herbst appliance (12b).
The following was established in the course of diagnostic model analysis:
− width measurements according to Pont SI = 6.5 + 8 + 8 + 6.5 = 29 mm; P = (29*100)/80 = 36.5 mm, − patient’s anterior width P = 32 mm,
− anterior stenosis of dental arches = –4.5 mm, − patient’s posterior width = 43.5 mm,
− according to the indicator T = (29*100)/64 = 45.31 mm,
− posterior stenosis of dental arches = –1.81 mm. The following was established in the course of cephalometric analysis:
− significant increase in the upper incisors incli-nation angle = 127.63°,
− WITS = 9.18 mm,
− Decreased intermaxillary angle,
− anteriorization, − Overjet = 15.74 mm, − Overbite = –5.76 mm,
− Considerably reduced lower incisors APg dis-tance – 5.12 mm.
Three-stage treatment has been planned, in-cluding the following:
− preparation of the upper dental arch for fron-tal mandibular mobilization using a perma-nent ribbon arch appliance,
− fitting of the Herbst appliance,
− fitting of a permanent ribbon arch appliance following the removal of the Herbst appliance. The duration of therapy using the Herbst ap-pliance amounted to 7 months. As a result, a sub-stantial improvement of the patient’s profile was observed along with the smoothening of the chin
Fig. 7. Patient’s extraoral photograph after removal of
the Herbst appliance
Ryc. 7. Fotografia zewnątrzustna po zdjęciu aparatu
Herbsta
Fig. 8. Patient’s plaster models before orthodontic
treatment
Ryc. 8. Modele gipsowe pacjentki przed leczeniem
groove and the attainment of Angle class I with the canines. Angle class I for the first molars was achieved after fitting a ribbon arch appliance on the lower dental arch, which was aimed to align them and fitted following the removal of the Herbst
ap-pliance. A significant improvement in the patient’s profile was also obtained (Fig. 12b). The state of the patient’s dentition is illustrated in figure 13.
Diagnostic model analysis following the Herbst appliance treatment:
Fig. 10. Patient’s plaster models – shape of dental arches before and after therapy Ryc. 10. Modele gipsowe pacjentki – kształt łuków zębowych przed leczeniem i po nim Fig. 9. Patient’s plaster models in occlusion before and after therapy
Fig. 11. Patient’s profile images: before treatment (a) and after removal of the Herbst appliance (b) Ryc. 11. Zdjęcia profilu pacjentki: przed leczeniem (a) i po zdjęciu aparatu Herbsta (b)
Fig. 12. Teleradiographic images: before treatment (a) and after removal of the Herbst appliance (b) Ryc. 12. Zdjęcia teleradiograficzne: przed leczeniem (a) i po zdjęciu aparatu Herbsta (b)
Fig. 13. Intraoral images after removal of the Herbst
appliance (b)
Ryc. 13. Zdjęcia wewnątrzustne po zdjęciu aparatu
− anterior width P = 37.5 mm (excess of 1 mm), − posterior width T = 49.5 mm (excess of
0.19 mm).
Cephalometric analysis following the Herbst appliance treatment:
− upper incisors inclination angle = 108.91°, − WITS = 2 mm,
− overjet = 4.11 mm, − overbite = 2.20 mm,
− lower incisors APg distance = 0.40 mm. As one of the alternatives of orthodontic
treat-ment of patients with skeletal class II malocclu-sion, the Herbst appliance provides an efficient method of improving the occlusion conditions in adults. The observation of their treatment, com-bined with several years of clinical observations, allowed the authors to consider this method to be useful, as proven by the immediate and lasting aesthetic results stemming from the restructuring of some elements of the masticatory organ, as well as the high level of patient satisfaction following several months of treatment.
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Address for correspondence:
Ryszard Koczorowski Department of Gerodontology Poznan University of Medical Sciences Bukowska 70
60-812 Poznań Poland
Tel.: +48 61 854 70 50 e-mail: rkoczor@ump.edu.pl Conflict of interest: None declared Received: 21.01.2014
Revised: 11.03.2014 Accepted: 6.04.2014
Praca wpłynęła do Redakcji: 21.01.2014 r. Po recenzji: 11.03.2014 r.
